1. Field of the Invention
The present invention relates to apparatus which can be used to add strongly reacting materials into a melt. 2. The Prior Art
Structures which can be used to add strongly reacting materials such as magnesium into a melt such as an iron melt to form, for example, cast iron with spheroidal graphite, are known. For example, in German Publication No. 2 208 960 such a structure is shown which includes an open vessel in which the melt is contained, a protective top which covers the open top of the vessel, a filling tube which extends through the protective top into the inside of the vessel, and a dip container which is attached to the filling tube by a conically flaired end and which has an internal reaction chamber which is in communication with the melt in the vessel and is supplied with the strongly reacting materials by way of the filling tube. The dip container includes an outer portion which is composed of a refractory material and an inner portion in the form of a basket-shaped metal container, the basket-shaped metal container adding a certain stability to the dimensions of the internal reaction chamber.
However, the intense heating of the filling tube and the almost explosive reactions in the dip container which occur during the immersion process lead to the formation of cracks and often to the destruction of either the refractory material portion of the dip container or else the filling tube in the area of its attachment to the dip container. When this happens, the contents of the internal reaction chamber will pour into the melt during the immersion process, leading to an uncontrollable situation which can result in destruction of the processing vessel or the protective top. This in turn can lead to a molten metal overflow which, obviously, is hazardous for the equipment operators who are nearby. The cracks and equipment damage which occur during the immersion process occur primarily in the area of the sheathed filling tube, namely, at the location where the dip container is attached to the filling tube. However, it can also occur on the wall forming the reaction chamber.
It is an object of the present invention to provide an apparatus for adding strongly reacting materials to a melt which can withstand both the thermal stresses and the high vapor pressures resulting from the chemical reactions therein.